Artillery shells are equipped with a safety and arming device (S&A) that permits detonation of the carried explosive only after the projectile has experienced a valid progression of physical launch conditions, including the huge initial acceleration (10,000–80,000 g). The arming device functions with sequential interlocks to remove a barrier in the fire train and/or to move out-of-line fire-train components into alignment. Once armed, the device can be fused with, e.g., an electrical discharge or a laser pulse. For safety, the S&A is required to be able to withstand a munitions mishandling drop from 40 ft. without damage or arming.
A typical arming device is centimeter sized and piece part assembled using screws, pins, springs, and tight-tolerance machined components. Shelf life is affected by the use of dissimilar materials and by the need for lubrication. Recent arming device modernizing efforts have been motivated by lower cost, weight, and volume. One such arrangement described by C. H. Robinson in U.S. Pat. No. 6,167,809 entitled “Ultra-Miniature, Monolithic, Mechanical Safety-and-Arming Device for Projected Munitions” is directed towards a monolithic metal (nickel) device fabricated using the LIGA micro machining process.
Notwithstanding the recent improvements made in these arming devices, there is a continuing need for further miniaturization and improved safety of arming devices.